After a few more gray hairs and a number of curses I have finally managed to link my cloud via WebDAV over SSL as a network drive in Windows.
The main problem was the self-signed certificate.
On Windows the certificate needs to be installed and declared to be safe.
Finally these steps worked for me.
After some complications, he is now finally here - the Banana Pi.
This requires a LEMP installation, as described here: Nginx, MySQL and PHP
This manual is written for an banana Pi, but it should also work for a Raspberry Pi or Beaglebone Black.
Step 1: Set up Nginx with SSL
These create the directory /etc/ssl/nginx, change to the directory and create a self-signed certificate.
Now that I finally had my little server, I wanted to sync all my stuff from a variety of electronic devices: ie the working files on different computers, and also the calendar data and addresses should finally be in sync on all devices.
After a quick search I am first came to OwnCloud. A truly worry-free solution and also really easy to install.
OwnCloud offers: